5-year clinical outcome of the ESTOIH trial comparing the short-bite versus large-bite technique for elective midline abdominal closure

One-third of the population in industrialised countries will undergo abdominal surgery in their lifetime [1]. Burst abdomen is the most feared short-term complication, and incisional hernia is the most commonly observed long-term complication after midline incision. The incidence of incisional hernia development is reported to be 30% two years and up to 60% five years after surgery, depending on the patient's risk factors, the type of incision used to open the abdominal cavity, surgical settings (elective or emergency), and the choice of suture technique for abdominal wall closure [2]. This implies that the incidence of incisional hernia has been significantly underestimated in previous trials with a short follow-up of one year; therefore, an extended follow-up is essential to draw conclusions about the best surgical approach [3].

The Inline Meta-Analysis published in 2010 indicated that a long-term absorbable monofilament in the continuous suture technique should be favoured to close elective median laparotomies [4]. A Cochrane Review published in 2017 confirmed this finding; however, no recommendation was made regarding the short bite technique [5]. The first meta-analysis that compared short versus long stitches for abdominal wall closure was the MATCH Review [6]. A subgroup analysis of two randomised controlled trials showed that the incisional hernia rate was significantly lower in the short-bite group than in the long-bite group [7, 8]. The authors concluded that a long-term, absorbable monofilament suture should be applied using the continuous short-bite technique to decrease the incidence of incisional hernias.

The recent European Hernia Society (EHS) guidelines for elective median abdominal wall closure currently contain a strong recommendation regarding the use of a continuous suture. In contrast, only a weak recommendation can be made regarding the short-bite technique and suture material due to the lack of available evidence [9].

Previous studies have used a polydioxanone-based suture as a long-term absorbable monofilament suture material. This type of suture material is absorbed in the human body within 180 days postoperatively, and it also loses 50% of its tensile strength during the first 30 days [10]. However, tt is known that the abdominal fascia regains only 70% of its initial strength 1 year after primary laparotomy [11]. Data have also shown that 52% of incisional hernias occur within 6 months after surgery, 60% within 1 year, and 79% within two years postoperatively [11, 12], which implies that the absorption rate of traditional suture materials might be too fast, and prolonged suture support may be needed for adequate abdominal wall closure [11]. Therefore, a new ultra-long-term absorbable, elastic, monofilament suture material named"Monomax"made of poly-4-hydroxybutyrate homopolymer was developed in 2007 and analysed for the first time in human beings regarding its safety and efficacy in the ISSAAC trial [13, 14]. This suture material combines high tensile strength with a high degree of pliability among the currently available absorbable monofilament sutures. It exhibits several properties relevant to clinical use, including high elasticity, prolonged strength retention, low tissue drag, and reliable knot security. These characteristics align with key criteria for an effective suture material for midline abdominal wall closure. Animal tests demonstrated that this type of suture material exhibited excellent biocompatibility and good physiological tissue integration, without causing tissue irritation or infection [13]. These properties have been confirmed in the ISSAAC multicentric, prospective, human clinical trial, and the results also indicated that the suture material is safe and efficient for abdominal wall closure after primary midline laparotomy [15].

A second multicentric, international, prospective trial (MULTIMAC) performed under clinical routine settings proved the safety and effectiveness of the poly-4-hydroxybutyrate suture material for midline as well as for transverse abdominal wall closures even in high-risk patients (obese, AAA, and diabetes patients) regarding the short-term complications such as burst abdomen and wound infections [16]. Since both the ISSAAC and MULTIMAC studies utilized the poly-4-hydroxybutyrate suture material in the long-stitch technique for fascia closure, a randomised controlled trial named ESTOIH was designed in 2013 to compare the short-bite technique with the long-bite technique in combination with the poly-4-hydroxybutyrate suture material regarding short- and long-term clinical outcomes [17]. Based on the need for a significantly longer follow-up period, the ESTOIH study is the first RCT to analyse small bites versus large bites for fascia closure, including a five-year postoperative examination. Short-term results, focusing on burst abdomen and surgical site infections, showed a trend toward a lower burst abdomen rate in the short-stitch group, implying that the elastic, ultra-long-term absorbable monofilament was associated with an overall low complication rate, including wound infections [18]. Long-term follow-up findings of the ESTOIH study 1 and 3 years after surgery showed that at both time points, the incisional hernia rate was lower and the quality of life significantly higher in the small-bite group than in the large-bite group [19, 20].

In this article, we report for the first time the clinical findings obtained after five years regarding the comparison of small bites versus large bites for elective midline laparotomy closure using an elastic, ultra-long-term absorbable, poly-4-hydroxybuyrate, monofilament suture material.

We have published our a priori study protocol of the ESTOIH study, in which the study design, participant inclusion and exclusion criteria, intervention details, randomisation method, and statistics were described [17]. Furthermore, the ESTOIH clinical short-term results obtained 30 days postoperatively, as well as the 1-year and 3-year outcomes, have been reported previously [18‐20].

This study represents the first randomised controlled trial (RCT) to report 5-year follow-up data comparing short-versus long-stitch techniques for midline abdominal wall closure. In total, 362 patients were included in the intention-to-treat (ITT) analysis, with 175 and 187 patients in the short-bite and long-bite groups, respectively. Our findings indicate that while the incisional hernia (IH) rate increased over time in both groups, the short-stitch group consistently exhibited a lower IH rate than the long-stitch group.

Importantly, both groups showed an increase in IH rates from 1 to 5 years postoperatively; however, the long-stitch group consistently exhibited higher IH rates at every time point. Kaplan–Meier analysis confirmed this observation, with a stable separation of the IH incidence curves between the two groups from 1 to 5 years, further suggesting that the short-stitch approach may offer a more durable protective effect against hernia formation.

The data presented here align with the growing body of evidence supporting the superior efficacy of the short-stitch technique, particularly when combined with an extra-long-term absorbable, elastic, monofilament poly-4-hydroxybutyrate (P4HB) suture. The very low IH rate observed in the short-stitch group at 5 years underscores the potential of this technique to achieve sustained results over time, even in long-term follow-up.

Furthermore, the patient-reported outcomes in this study also favoured the short-stitch group. The EQ-5D visual analogue scale (VAS) and EQ-5D index scores were significantly higher at 1 and 3 years in the short-stitch group, reflecting not only a reduced hernia burden but also an improvement in the overall quality of life. These findings reinforce the notion that surgical techniques that minimise postoperative complications, such as incisional hernia, can contribute to better long-term patient satisfaction and functional recovery.

It is important to distinguish between the effects of the suture technique and suture material. In the ESTOIH trial, both groups received the same extra-long-term absorbable elastic monofilament suture, allowing for a comparison of the technique alone. The lower hernia rate observed in the short-stitch group reflects the effect of the technique, while the low absolute hernia rates in both groups, relative to historical controls, may be partly attributed to the favourable material properties. When comparing the results of the ESTOIH study with those of other studies, our results seem particularly noteworthy. In the ESTOIH study, the 5-year IH rates in both arms were lower than the 1-year rates observed in the STITCH study [8]. This supports the hypothesis of a strictly standardised technique in combination with a highly elastic, ultralong resorbable suture material (Monomax®) used in the ESTOIH study compared to the suture material of polydioxanon (PDS®) used in the STITCH trial. Moreover, the hernia rate in the long-stitch group of the ESTOIH study was significantly lower than that reported in the suture-only group of the PRIMA trial (53.4%) after five years. In this study, a prophylactic mesh in the onlay and retrorectus positions was compared to a large bite closure using the all-in-one stitch technique with PDS®. Compared to the 1-year results of the ISAAC study, a historically controlled, single-arm, multicentre, prospective study evaluating the safety of MonoMax® with an IH rate of 14%, the 5-year data from the ESTOIH study are also remarkable. [14, 23, 24]. Taken together, the combination of a refined short-stitch technique and modern suture material may provide optimal outcomes for elective midline closure.

These comparisons highlight the progress in surgical techniques and material selection, with the short-stitch technique emerging as a more effective approach for reducing IH formation.

Suture materials likely play a relevant role in influencing these outcomes. The use of Monomax®, a slowly absorbable monofilament suture, has shown promising results in previous studies. Lai et al. reported less postoperative pain with the short-stitch technique than with the long-stitch technique using Monomax® [25]. These findings also reflect those of the ESTOIH study. Probst et al. demonstrated the suitability in recurrent hernia repairs, while Uske et al. and Sujatha et al. found lower IH rates when using Monomax® compared to non-resorbable polypropylene sutures [26‐28]. These studies support the hypothesis that the combination of short-stitch techniques with advanced suture materials may contribute to lower complication rates and improved long-term outcomes.

In terms of economic impact, recent studies by Gokani et al.; Lwin et al. and Millbourn et al. have demonstrated the cost-effectiveness of the short-stitch technique [29‐31]. The reduction in IH rates and the associated decrease in the need for reoperations can lead to significant long-term cost savings for both healthcare systems and patients. This potential economic advantage, coupled with the clinical benefits demonstrated in the present study, further strengthens the case for adopting the short-stitch technique as the preferred approach for abdominal wall closure.

Despite the available evidence, the short-stitch technique does not appear to be widely used internationally. Numerous surveys conducted in different countries have confirmed this situation. Barriers to implementation include ignorance of the scientific data, the argument of increased closure time, and failure to follow the recommendation to incorporate the short-bite technique in the updated EHS and AHS guidelines for abdominal wall closure in daily routine (32–36). In the survey conducted by Cochrun et al. (32), various problem areas of implementation were evident. These include the training and practice environment, as well as the associated decision-making of surgeons, which is primarily mediated by mentors and colleagues who either support or oppose the results, and the influence of peers, with anecdotal negative results often taking precedence over evidence-based results. In the UK national survey by Messenger et al. (33), the adoption of the short-stitch technique was also very low at 19.9%. The most common barriers to the use of small bites were a perceived lack of evidence and a perception of low personal incision hernia rates. Not surprisingly, a survey of colorectal surgeons in Spain (34) revealed that a closure technique using continuous sutures was employed in 96.23% of cases, with a single layer in 81.13% of cases, and a suture size of USP 1 in 58.49% of cases, suggesting the use of large-bite sutures only.

In the context of short-stitch method implementation, it can be concluded that only a combination of comprehensive education on the scientific evidence of the incisional hernia rate and closure methods, as well as on the technical aspects of the short-stitch closure procedure, in the context of workshops in the different surgical disciplines with open access surgery, can be achieved in the long term.

Several limitations of this study should be mentioned. First, despite the inherent challenges of long-term follow-up, 84% of the participants completed the 5-year assessment, with attrition rates balanced across the treatment arms, minimising the risk of systematic bias. Although follow-up rates were high and evenly distributed across groups, we acknowledge that some attrition may have been related to deteriorating health or reduced quality of life, an inherent limitation of long-term observational analyses.

Second, ensuring a uniform suture technique across trial centres and over time is inherently challenging. In the ESTOIH trial, the consistent application of the assigned techniques was supported by protocol-defined metrics, such as the suture length-to-wound length (SL:WL) ratio, complemented by structured training and regular site monitoring, underscoring the procedural integrity of this multicentre study.

Third, as reported in the initial publication, the trial was terminated after the interim analysis because of low recruitment and failure to achieve the predefined study aim. Consequently, the final sample size was below the target, limiting the statistical power of long-term comparisons. The absence of statistical significance at 5 years may reflect a smaller absolute difference and reduced power rather than a loss of effect.

Finally, in the 1-year multivariable analysis, a high BMI (≥ 30 kg/m²) emerged as a significant independent risk factor, whereas other comorbidities were not associated with hernia formation. Although comorbidities may change over time, the risk of incisional hernia is largely determined by perioperative factors. Therefore, longitudinal tracking of evolving comorbidities was not included in the ESTOIH trial protocol, and no conclusions can be drawn from our data regarding the role of evolving comorbidities during long-term follow-up.

In conclusion, the 5-year results of this study suggest that the short-stitch technique, particularly when combined with an extra-long-term absorbable, elastic, monofilament P4HB suture, offers significant advantages in terms of both clinical outcomes and patient-reported quality of life. While the difference in IH rates between the two techniques was not statistically significant at 5 years, the lower rates observed in the short-stitch group at every time point suggest a more favourable long-term outcome. These findings, along with supporting evidence from other studies, highlight the short-stitch technique as a promising approach for reducing incisional hernia formation and improving patient quality of life after abdominal wall closure following midline laparotomy.